Most DSLR?s have 2 mirrors one for viewing the display from the front sensor and one for focus. More moving parts make for a bigger and heavier camera and sometimes the camera shakes. The mirror less camera has five axis image stabilized sensor and obviously contains no moving mirror. No moving parts make the camera easy to handle. The best part about mirror less camera is when you use it with camera flash or studio lights, what you see is what you get there is no requirement to chimp.